/* ----------------------------------------------------------------------
* Copyright (C) 2010 ARM Limited. All rights reserved.
*
* $Date:        15. February 2012
* $Revision: 	V1.1.0
*
* Project: 	    CMSIS DSP Library
* Title:		arm_dot_prod_q7.c
*
* Description:	Q7 dot product.
*
* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
*
* Version 1.1.0 2012/02/15
*    Updated with more optimizations, bug fixes and minor API changes.
*
* Version 1.0.10 2011/7/15
*    Big Endian support added and Merged M0 and M3/M4 Source code.
*
* Version 1.0.3 2010/11/29
*    Re-organized the CMSIS folders and updated documentation.
*
* Version 1.0.2 2010/11/11
*    Documentation updated.
*
* Version 1.0.1 2010/10/05
*    Production release and review comments incorporated.
*
* Version 1.0.0 2010/09/20
*    Production release and review comments incorporated.
*
* Version 0.0.7  2010/06/10
*    Misra-C changes done
* -------------------------------------------------------------------- */

#include "arm_math.h"

/**
 * @ingroup groupMath
 */

/**
 * @addtogroup dot_prod
 * @{
 */

/**
 * @brief Dot product of Q7 vectors.
 * @param[in]       *pSrcA points to the first input vector
 * @param[in]       *pSrcB points to the second input vector
 * @param[in]       blockSize number of samples in each vector
 * @param[out]      *result output result returned here
 * @return none.
 *
 * <b>Scaling and Overflow Behavior:</b>
 * \par
 * The intermediate multiplications are in 1.7 x 1.7 = 2.14 format and these
 * results are added to an accumulator in 18.14 format.
 * Nonsaturating additions are used and there is no danger of wrap around as long as
 * the vectors are less than 2^18 elements long.
 * The return result is in 18.14 format.
 */

void arm_dot_prod_q7(
    q7_t* pSrcA,
    q7_t* pSrcB,
    uint32_t blockSize,
    q31_t* result)
{
	uint32_t blkCnt;                               /* loop counter */

	q31_t sum = 0;                                 /* Temporary variables to store output */

#ifndef ARM_MATH_CM0

	/* Run the below code for Cortex-M4 and Cortex-M3 */

	q31_t input1, input2;                          /* Temporary variables to store input */
	q31_t inA1, inA2, inB1, inB2;                  /* Temporary variables to store input */



	/*loop Unrolling */
	blkCnt = blockSize >> 2u;

	/* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
	 ** a second loop below computes the remaining 1 to 3 samples. */
	while(blkCnt > 0u) {
		/* read 4 samples at a time from sourceA */
		input1 = *__SIMD32(pSrcA)++;
		/* read 4 samples at a time from sourceB */
		input2 = *__SIMD32(pSrcB)++;

		/* extract two q7_t samples to q15_t samples */
		inA1 = __SXTB16(__ROR(input1, 8));
		/* extract reminaing two samples */
		inA2 = __SXTB16(input1);
		/* extract two q7_t samples to q15_t samples */
		inB1 = __SXTB16(__ROR(input2, 8));
		/* extract reminaing two samples */
		inB2 = __SXTB16(input2);

		/* multiply and accumulate two samples at a time */
		sum = __SMLAD(inA1, inB1, sum);
		sum = __SMLAD(inA2, inB2, sum);

		/* Decrement the loop counter */
		blkCnt--;
	}

	/* If the blockSize is not a multiple of 4, compute any remaining output samples here.
	 ** No loop unrolling is used. */
	blkCnt = blockSize % 0x4u;

	while(blkCnt > 0u) {
		/* C = A[0]* B[0] + A[1]* B[1] + A[2]* B[2] + .....+ A[blockSize-1]* B[blockSize-1] */
		/* Dot product and then store the results in a temporary buffer. */
		sum = __SMLAD(*pSrcA++, *pSrcB++, sum);

		/* Decrement the loop counter */
		blkCnt--;
	}

#else

	/* Run the below code for Cortex-M0 */



	/* Initialize blkCnt with number of samples */
	blkCnt = blockSize;

	while(blkCnt > 0u) {
		/* C = A[0]* B[0] + A[1]* B[1] + A[2]* B[2] + .....+ A[blockSize-1]* B[blockSize-1] */
		/* Dot product and then store the results in a temporary buffer. */
		sum += (q31_t)((q15_t) * pSrcA++ * *pSrcB++);

		/* Decrement the loop counter */
		blkCnt--;
	}

#endif /* #ifndef ARM_MATH_CM0 */


	/* Store the result in the destination buffer in 18.14 format */
	*result = sum;
}

/**
 * @} end of dot_prod group
 */
